The reality star fumbled over her words when introducing newcomers 5 Seconds of Summer on Sunday at the Billboard Music Awards in Las Vegas.

"And now we welcome ... One ...," the 21-year-old said, seeming to almost say One Direction, as she put her head down. "Guys, I'm the worst reader."

Jenner then introduced a video featuring the Australian pop group, who performed their rising hit "She Looks So Perfect."

Other performers Sunday at the MGM Grand Garden Arena included Florida Georgia Line and Luke Bryan, who were crowd favorites when they performed "This Is How We Roll." Even Carrie Underwood and her hockey player-husband Mike Fisher sang along.

Ariana Grande, who turns 21 next month, was semi-racy when she sang her hit "Problem" in a mini black and white dress alongside rapper Iggy Azalea. Grande was nominated for best new art, but she lost to breakthrough New Zealander Lorde.

Lorde entered the night as the top contender, along with Imagine Dragons, where the Billboard Music Awards marked a homecoming for Imagine Dragons.

The Las Vegas-based rockers won the night's first trophy, top rock album, for their 2012 debut "Night Visions" at the awards show Sunday in Las Vegas.

"We've been a band for five years and we played small bars for many of those years, and we wouldn't be here today if it wasn't for people that believed in our band, in our small band that started here in Las Vegas from the very beginning," leader Dan Reynolds told the audience at the MGM Grand Garden Arena.

He then thanked radio, family and management for their support, adding with a yell at the end: "And Billboard!"

Imagine Dragons is also up for the night's biggest honor, top award. The group will battle Perry, Miley Cyrus, Bruno Mars, and Justin Timberlake, who won top Billboard 200 album and accepted in a video as he's on tour outside of the country. He sang "thank you" along with his band.

Pitbull and Jennifer Lopez kicked off the awards show with a colorful performance of the World Cup anthem, "We Are One (Ole Ola)," where Brazilian singer Claudia Leitte also joined in.

Other performers include Robin Thicke and John Legend, but Michael Jackson's hologram may be the night's most anticipated moment.

The Billboard Music Awards may feature a hologram of the pop icon as part of a "history-making performance" dick clark productions is promising viewers and feverish Jackson fans. It would be another way his record label, Epic, is promoting his second posthumous album, "Xscape," released last week. The album's first single, "Love Never Felt This Good," debuted earlier this month when Usher danced while the song played at the iHeartRadio Music Awards.

A federal judge ruled Friday that the Billboard Music Awards can use a hologram of the deceased pop icon, rejecting efforts from tech companies seeking to block the digital performance. Jackson died in 2009.